Variable displacement pump



L. E. TOPHAM VARIABLE DISPLACEMENT PUMP Oct. 5, 1948.

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l T l l I l I l l I l ll l J I I I I I I l ll Filed Oct. 2, 1943 a c h zz I 3 Sheets-Sheet 2 L. E. TOPHAM VARIABLE DISPLACEIIENT PUHP [nven forLaurcnce E Topl'um Oct. 5, 1948.

Filed Oct. 2, 1943 Patented Oct. 5, 1948 VARIABLE DISPLACEMENT PUMPLaurence E. Topham, Wenham, Mass, assignor to United Shoe MachineryCorporation, Flemington, N. J a corporation of New Jersey ApplicationOctober 2, 1943, Serial No. 504,755 3 Claims. (Cl. 103-38) provides arotatable piston mounted for reciprocation in a chamber, having fluidintake and exhaust ports, the end of the piston constituting avalvehaving a port operable successively during rotation of the pistonto connect the intake and exhaust ports with the chamber. Preferably,and as illustrated, use is made of a plurality of pistons and chambers,the amount of discharge being varied by varying the length of stroke ofthe pistons. Preferably, too, the direction of flow of the fluid isreversed when desired by shifting the pistons longitudinallyof thechambers, so that the intake and exhaust portions of the cycle of thetwo pistons are interchanged, that is, shifted in phase by 180.

These and other features of the invention are disclosed in the followingspecification and in the accompanying drawings, and are pointed out inthe claims.

In the drawings,

Fig. 1 is a plan view, partly in section, of a pump constructed inaccordance with one embodiment of my invention;

Fig. 2 is a vertical cross sectional view of the mechanism shown in Fig.1;

Fig. 3 is a longitudinal cross sectional view, on an enlarged scale,through one of the pump cylinders;

Fig. 4 is a transverse cross sectional view, on an enlarged scale, takenalong line IVIV of Fig.

Figs. 5 and 6 are diagrammatic viewsillustrating the operation of themechanism;

Fig. 7 is a side view, partly in section, of the mechanism for varyingthe stroke of the pump;

Fig. 8 is a cross sectional view taken along line VIII-VIII of Fig. 7;

Fig. 9 is a side view, partly in section, of the mechanism shown in Fig.7 after operation of the manual control means; and

Fig. 10 is a cross sectional view taken along line XXof Fig. 9.

The pump mechanism may comprise any suitable number of pump units, eachincluding two pump cylinders having pistons positioned therein and asingle piston rod or shaft connecting the pistons. Figs. 1 and 2 show ahousing 10, having therein two of such units. Preferably, the housing isa casting having four parallel fluid passages l2, l4, l6 and I8extending transversely thereof, the passages 12 and I4 being locateddirectly above the passages l6 and I8, respectively. The passages I2 and16 are connected by two vertically extending passages 20, and thepassages l4 and I8 are similarly connected by vertical passages 22. Eachof the vertical passages is provided with a pum cylinder 24 extending ina horizontal direction, the cylinders on opposite sides of the centralportion of the housing being in alinement with each other. In each pairof alined cylinders are located pistons 26 and 28, which are joined by asingle connecting rod or shaft 30.

One end of each of the passages l2, l4, l6 and I8 is closed by a plug32. The passage I2 is connected with the passage l8 by pipe connections34 leading to fluid pipe 36. Passages I4 and I6 are likewise connectedtogether by pipe connections 38, which lead to a fluid pipe 40. Eitherof the fluid pipes may serve as an intake or a discharge pipe forsupplying to or discharging from the pump cylinders the fluid set inmotion by the operation of the pistons.

Each of the cylinders 24 comprises a plug 42 (Fig. 3) having a reducedbearing ortion 44 extending transversely of the vertical passages 20 or22, and has a machined bore 46 provided with two ports 48 and 50 inalinement with the vertical passages. The ends of the cylinders areclosed by packing 52 held in position by Washers 54 and bolts 56.

The end portion of each piston constitutes a valve for controlling thedirection of flow of the fluid relatively to the pump cylinders. Asshown in Fig. 3, the end of each piston is provided with a cylindricalopen-ended chamber 58, extending axially of the piston and having anarrow elongated slot or valve port cut in its side wall. The wall ofthe chamber acts to prevent flow of fluid through the vertical passage(20 or 22), except when the slot 60 is alined with one or the other ofthe ports 48 or 50.

As will be hereinafter described, each piston is arranged forreciprocation in its cylinder and for continuous rotation about itsaxis. In the position shown in Fig. 3, with the piston moving to theright and rotating in a clockwise direction,

as indicated by the arrows, it will be noted that the valve port 6!] isabout to be alined with the port 50, with the result that fluid in thecylinder will be forced out through the port. Upon further rotation ofthe cylinder, during which the piston is moved toward the left in Fig.3, the slot will become alined with the port 48 and, if fluid issupplied thereto, it will pass by suction into the cylinder ready forejection upon the next compression stroke of the piston. the upperportion of Fig. 1, the pump unit is in position with the piston at theright side of the figure on the compression stroke, during which fluidis forced out of the cylinder and discharged into the fluid pipe 38,while at the same time the piston at the left side of the figure is onthe suction stroke and will receive fluid from the fluid pipe 34.

In order to rotate the shafts 38 with their associated pistons. eachshaft is provided witha pinion 82 mounted on a shaft 63 in' bearings 84in the housing and meshing with a gear 88 mounted upon a shaft 88carried by the housing and arranged to be driven by a pulley 18.

The mechanism by which the pistons are reciprocated whendesired will nowbe described. Each shaft 38 is provided, midway between the pistons,with two oifset portions 12 extendinga-t an angle of approximately 30 tothe axis of the shaft, and having between them a cylindrical member orcrank 14, best shown in Figs. '7, 8, 9 and 10. Surrounding the crank aretwo bearing members 18, from which extend in opposite directions pivots18, the pivots and bearings being secured in position by bolts 88. Thepivots are in turn mounted in bearings 82 secured by screws 84 to agimbal 86. Each of the gimbals is provided with trunnions 88 extendingat right angles to the axis of the pivots, the trunnions being mounted,as shown in Fig. l, in levers 88 which are mounted on pivots 92, 84 and86 on the housing. The position of the trunnions can be shifted in aheightwise direction by means of racks 88 on the levers 98 and meshingwith gear segments I88 secured to a bracket I82 pivotally mounted uponthe housing. The bracket is carried by pins I84 in the housing, and ismounted with its axis eccentric to the axes of the pins, with the resultthat, upon rotation of the pins by'a lever I88, the racks 88 will berotated and moved outwardly. thus effecting rotation of the levers 98about their pivots and resulting in the raising or lowering of thetrunn-ions 88. Thus, the member 14 during rotation constitutes a conicalcrank, the position of the apex of the cone of which is variable. Thisconstruction is such that, upon rotation of the piston rods, the crankswill rotate, effecting an oscillating movement of the pivots 18 aboutthe axes of the trunnions.

If the trunnions are positioned with their axes intersecting the mainaxis of the shaft 38, as shown in Figs. 7 and 8, the gimbal with itspivots will oscillate back and forth through an angle of As shown inadjustments of the gimbal 88. In Fig. 5, the gimbal is indicated in theposition in which the axis of its trunnions 88 intersect the axis of theshaft 38. After rotation of the shaft through 188, the parts will assumethe positions indicated in dot-ted lines. It is to be noted that thepivots 18 have oscillated about the axes of the trunnions through anangle of about 60, and that no reciprocating movement of the shaft hastaken place.

In Fig. 6, the gimbal is indicated in position with its trunnions belowthe axis of the shaft 38. After 180 of rotation of the shaft, the partsare in the positions indicated in dotted lines. In this instance thegimbal has also moved through an angle of about 60", but a longitudinalmovement has been imparted to the shaft.

It is to be noted that the lever I86 can be moved during the operationof the mechanism to vary the length of the stroke of the pistons, themovement of the lever in itself resulting in a longitudinal movement ofthe pistons to the right or to the left, independently of the drive ofthe mechanism. If, instead of moving the lever in a direction to lowerthe trunnions, the lever is moved to raise them above the main axis ofthe pistons, the pistons are moved to the left, with the result that theactionof the pump is reversed. That is, what was thedntake now beaboutwithout effecting any reciprocating movement of the shaft. However, ifthe lever I88 is moved in such away as to position the trunnions belowthe main axis of the shaft, as shown in Figs. 9 and 10, upon rotation ofthe shaft, the gimbal will oscillate about the axis of the trunnions,then positioned below the main axis of the shaft, with the result that alongitudinal reciprocating movement is imparted to the shaft and to thepiston rods. The amount of the movement of the shaft corresponding tothe stroke of the pistons will vary, depending upon the position of thetrunnion-s relatively to the axis of the shaft, the stroke beingincreased as the distance between the two axes increases.

Figs. 5 and 6 illustrate diagrammatically the variation in movement ofthe shaft for different comes the discharge side of the pump, and viceversa. Thus, the position of the parts shown in Fig. 3 is 180 out ofphase with the position the parts would occupy if the trunnions weremoved to a point an equal distance from the main axis of the shaft.Thus, the mechanism provides means for facilitating the operation of thepump at different discharge capacities, and also provides for reversingthe direction of flow of fluid through the pump. In other words. thefluid can be caused to flow through the pump in either direction atcapacities varying from zero to a maximum. In view of the fact that theparts are rotated continuously during the operation of the pump, evenwhen the discharge is zero, the static friction is reduced to a minimum.

It will be noticed that the two pump units shown in Fig. 1 are out ofphase. That is,

the compression stroke of the unit in the lower part of the figure willtake place one-quarter of a cycle after the operation of the unit shownin the upper portion of the figure, other parts of the operation beingin the same relation. This contributes to the smoothness of operation ofthe pump tending to balance the force acting and to cause a smoothdischarge of fiuid.

Having described my invention, what I claim as new and desire to secureby Letters Patent of the United States is:

1. A pump comprising a pump cylinder, fluid passages extending from theside walls of the cylinder, a crank shaft, a, piston carried at the endof the crank shaft and being positioned in the cylinder between thefluid passages, the piston having an open-ended chamber extendinglongitudinally of the pump cylinder and an elongated valve portextending through the side wall of the chamber, meansv for continuouslyrotatin the crank shaft and piston, a crank on the crank shaft, meansoperable from the crank itself to effect reciprocation of the shaft andiston whereby the valve port is successively brought into alinement withthe fluid passages duringreciprocatory and rotary movements of thepiston and means associated with the crank for varying the length ofstroke of the piston.

2. A pump comprising two pump cylinders, a crankshaft extending betweenthe cylinders, pistons on the ends of the shaft and positioned withinthe cylinders, fluid passages extending from each of the cylinders uponopposit sides of each of the pistons, each of the pistons having anopen-ended chamber therein and a valve port extending through the sidewall of the chamber, means for continuously rotating the crank shaft topresent each of the valves successively in alinement with the fluidpassages in its cylinder, fluid supply means connected to the severalfluid passages, means for reciprocating the crank shaft during rotationthereof thereby to effect fluid discharge from one of the cylinders andfluid intake into the other cylinder during each cycle of opera tion,and means for varying the amount of reciprocating movement of the crankshaft thereby to vary the amount of fluid intake and discharge from zero.to a. maximum.

3. A pump comprising a housing having two fluid passages extending inparallel relation, a pump cylinder located in each of the passages andextending transversely thereof, the cylinders being in alinement witheach other, a crank shaft extending between the cylinders, pistonslocated upon the ends of the crank shaft, fluid connections extendingbetween the upper end of one of the passages and from the lower end ofthe other of the passages, a fluid line leading to the connections, aplurality of ports in each of the cylinders communicating with thepassages, a valve carried by each of the pistons and comprising a hollowmember located in a cylinder, 3. port extending through the wall of thehollow; member, means for reciprocating the pistons, and means forcontinuously rotating the pistons during their reciprocating movementthereby successively to present the valve in alinement with the ports.

LAURENCE E. TOPHAM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

